NAME

       userdbctl - Inspect users, groups and group memberships

SYNOPSIS

       userdbctl [OPTIONS...] {COMMAND} [NAME...]

DESCRIPTION

       userdbctl may be used to inspect user and groups (as well as group memberships) of the
       system. This client utility inquires user/group information provided by various system
       services, both operating on JSON user/group records (as defined by the JSON User
       Records[1] and JSON Group Records[2] definitions), and classic UNIX NSS/glibc user and
       group records. This tool is primarily a client to the User/Group Record Lookup API via
       Varlink[3], and may also pick up drop-in JSON user and group records from /etc/userdb/,
       /run/userdb/, /run/host/userdb/, /usr/lib/userdb/.

OPTIONS

       The following options are understood:

       --output=MODE
           Choose the output mode, takes one of "classic", "friendly", "table", "json". If
           "classic", an output very close to the format of /etc/passwd or /etc/group is
           generated. If "friendly" a more comprehensive and user friendly, human readable output
           is generated; if "table" a minimal, tabular output is generated; if "json" a JSON
           formatted output is generated. Defaults to "friendly" if a user/group is specified on
           the command line, "table" otherwise.

           Note that most output formats do not show all available information. In particular,
           "classic" and "table" show only the most important fields. Various modes also do not
           show password hashes. Use "json" to view all fields, including any authentication
           fields.

       --json=FORMAT
           Selects JSON output mode (like --output=json) and selects the precise display mode.
           Takes one of "pretty" or "short". If "pretty", human-friendly whitespace and newlines
           are inserted in the output to make the JSON data more readable. If "short", all
           superfluous whitespace is suppressed.

       --service=SERVICE[:SERVICE...], -s SERVICE:SERVICE...
           Controls which services to query for users/groups. Takes a list of one or more service
           names, separated by ":". See below for a list of well-known service names. If not
           specified all available services are queried at once.

       --with-nss=BOOL
           Controls whether to include classic glibc/NSS user/group lookups in the output. If
           --with-nss=no is used any attempts to resolve or enumerate users/groups provided only
           via glibc NSS is suppressed. If --with-nss=yes is specified such users/groups are
           included in the output (which is the default).

       --with-varlink=BOOL
           Controls whether to include Varlink user/group lookups in the output, i.e. those done
           via the User/Group Record Lookup API via Varlink[3]. If --with-varlink=no is used any
           attempts to resolve or enumerate users/groups provided only via Varlink are
           suppressed. If --with-varlink=yes is specified such users/groups are included in the
           output (which is the default).

       --with-dropin=BOOL
           Controls whether to include user/group lookups in the output that are defined using
           drop-in files in /etc/userdb/, /run/userdb/, /run/host/userdb/, /usr/lib/userdb/. If
           --with-dropin=no is used these records are suppressed. If --with-dropin=yes is
           specified such users/groups are included in the output (which is the default).

       --synthesize=BOOL
           Controls whether to synthesize records for the root and nobody users/groups if they
           aren't defined otherwise. By default (or "yes") such records are implicitly
           synthesized if otherwise missing since they have special significance to the OS. When
           "no" this synthesizing is turned off.

       -N
           This option is short for --with-nss=no --synthesize=no. Use this option to show only
           records that are natively defined as JSON user or group records, with all NSS/glibc
           compatibility and all implicit synthesis turned off.

       --multiplexer=BOOL
           Controls whether to do lookups via the multiplexer service (if specified as true, the
           default) or do lookups in the client (if specified as false). Using the multiplexer
           service is typically preferable, since it runs in a locked down sandbox.

       --chain
           When used with the ssh-authorized-keys command, this will allow passing an additional
           command line after the user name that is chain executed after the lookup completed.
           This allows chaining multiple tools that show SSH authorized keys.

       --no-pager
           Do not pipe output into a pager.

       --no-legend
           Do not print the legend, i.e. column headers and the footer with hints.

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

COMMANDS

       The following commands are understood:

       user [USER...]
           List all known users records or show details of one or more specified user records.
           Use --output= to tweak output mode.

       group [GROUP...]
           List all known group records or show details of one or more specified group records.
           Use --output= to tweak output mode.

       users-in-group [GROUP...]
           List users that are members of the specified groups. If no groups are specified list
           all user/group memberships defined. Use --output= to tweak output mode.

       groups-of-user [USER...]
           List groups that the specified users are members of. If no users are specified list
           all user/group memberships defined (in this case groups-of-user and users-in-group are
           equivalent). Use --output= to tweak output mode.

       services
           List all services currently providing user/group definitions to the system. See below
           for a list of well-known services providing user information.

       ssh-authorized-keys
           Show SSH authorized keys for this account. This command is intended to be used to
           allow the SSH daemon to pick up authorized keys from user records, see below.

WELL-KNOWN SERVICES

       The userdbctl services command will list all currently running services that provide user
       or group definitions to the system. The following well-known services are shown among this
       list:

       io.systemd.DynamicUser
           This service is provided by the system service manager itself (i.e. PID 1) and makes
           all users (and their groups) synthesized through the DynamicUser= setting in service
           unit files available to the system (see systemd.exec(5) for details about this
           setting).

       io.systemd.Home
           This service is provided by systemd-homed.service(8) and makes all users (and their
           groups) belonging to home directories managed by that service available to the system.

       io.systemd.Machine
           This service is provided by systemd-machined.service(8) and synthesizes records for
           all users/groups used by a container that employs user namespacing.

       io.systemd.Multiplexer
           This service is provided by systemd-userdbd.service(8) and multiplexes user/group
           look-ups to all other running lookup services. This is the primary entry point for
           user/group record clients, as it simplifies client side implementation substantially
           since they can ask a single service for lookups instead of asking all running services
           in parallel.  userdbctl uses this service preferably, too, unless --with-nss= or
           --service= are used, in which case finer control over the services to talk to is
           required.

       io.systemd.NameServiceSwitch
           This service is (also) provided by systemd-userdbd.service(8) and converts classic
           NSS/glibc user and group records to JSON user/group records, providing full backwards
           compatibility. Use --with-nss=no to disable this compatibility, see above. Note that
           compatibility is actually provided in both directions: nss-systemd(8) will
           automatically synthesize classic NSS/glibc user/group records from all JSON user/group
           records provided to the system, thus using both APIs is mostly equivalent and provides
           access to the same data, however the NSS/glibc APIs necessarily expose a more reduced
           set of fields only.

       io.systemd.DropIn
           This service is (also) provided by systemd-userdbd.service(8) and picks up JSON
           user/group records from /etc/userdb/, /run/userdb/, /run/host/userdb/,
           /usr/lib/userdb/.

       Note that userdbctl has internal support for NSS-based lookups too. This means that if
       neither io.systemd.Multiplexer nor io.systemd.NameServiceSwitch are running look-ups into
       the basic user/group databases will still work.

INTEGRATION WITH SSH

       The userdbctl tool may be used to make the list of SSH authorized keys possibly contained
       in a user record available to the SSH daemon for authentication. For that configure the
       following in sshd_config(5):

           ...
           AuthorizedKeysCommand /usr/bin/userdbctl ssh-authorized-keys %u
           AuthorizedKeysCommandUser root
           ...

       Sometimes it's useful to allow chain invocation of another program to list SSH authorized
       keys. By using the --chain such a tool may be chain executed by userdbctl
       ssh-authorized-keys once a lookup completes (regardless if an SSH key was found or not).
       Example:

           ...
           AuthorizedKeysCommand /usr/bin/userdbctl ssh-authorized-keys %u --chain /usr/bin/othertool %u
           AuthorizedKeysCommandUser root
           ...

       The above will first query the userdb database for SSH keys, and then chain execute
       /usr/bin/othertool to also be queried.

EXIT STATUS

       On success, 0 is returned, a non-zero failure code otherwise.

ENVIRONMENT

       $SYSTEMD_LOG_LEVEL
           The maximum log level of emitted messages (messages with a higher log level, i.e. less
           important ones, will be suppressed). Either one of (in order of decreasing importance)
           emerg, alert, crit, err, warning, notice, info, debug, or an integer in the range
           0...7. See syslog(3) for more information.

       $SYSTEMD_LOG_COLOR
           A boolean. If true, messages written to the tty will be colored according to priority.

           This setting is only useful when messages are written directly to the terminal,
           because journalctl(1) and other tools that display logs will color messages based on
           the log level on their own.

       $SYSTEMD_LOG_TIME
           A boolean. If true, console log messages will be prefixed with a timestamp.

           This setting is only useful when messages are written directly to the terminal or a
           file, because journalctl(1) and other tools that display logs will attach timestamps
           based on the entry metadata on their own.

       $SYSTEMD_LOG_LOCATION
           A boolean. If true, messages will be prefixed with a filename and line number in the
           source code where the message originates.

           Note that the log location is often attached as metadata to journal entries anyway.
           Including it directly in the message text can nevertheless be convenient when
           debugging programs.

       $SYSTEMD_LOG_TID
           A boolean. If true, messages will be prefixed with the current numerical thread ID
           (TID).

           Note that the this information is attached as metadata to journal entries anyway.
           Including it directly in the message text can nevertheless be convenient when
           debugging programs.

       $SYSTEMD_LOG_TARGET
           The destination for log messages. One of console (log to the attached tty),
           console-prefixed (log to the attached tty but with prefixes encoding the log level and
           "facility", see syslog(3), kmsg (log to the kernel circular log buffer), journal (log
           to the journal), journal-or-kmsg (log to the journal if available, and to kmsg
           otherwise), auto (determine the appropriate log target automatically, the default),
           null (disable log output).

       $SYSTEMD_PAGER
           Pager to use when --no-pager is not given; overrides $PAGER. If neither $SYSTEMD_PAGER
           nor $PAGER are set, a set of well-known pager implementations are tried in turn,
           including less(1) and more(1), until one is found. If no pager implementation is
           discovered no pager is invoked. Setting this environment variable to an empty string
           or the value "cat" is equivalent to passing --no-pager.

           Note: if $SYSTEMD_PAGERSECURE is not set, $SYSTEMD_PAGER (as well as $PAGER) will be
           silently ignored.

       $SYSTEMD_LESS
           Override the options passed to less (by default "FRSXMK").

           Users might want to change two options in particular:

           K
               This option instructs the pager to exit immediately when Ctrl+C is pressed. To
               allow less to handle Ctrl+C itself to switch back to the pager command prompt,
               unset this option.

               If the value of $SYSTEMD_LESS does not include "K", and the pager that is invoked
               is less, Ctrl+C will be ignored by the executable, and needs to be handled by the
               pager.

           X
               This option instructs the pager to not send termcap initialization and
               deinitialization strings to the terminal. It is set by default to allow command
               output to remain visible in the terminal even after the pager exits. Nevertheless,
               this prevents some pager functionality from working, in particular paged output
               cannot be scrolled with the mouse.

           See less(1) for more discussion.

       $SYSTEMD_LESSCHARSET
           Override the charset passed to less (by default "utf-8", if the invoking terminal is
           determined to be UTF-8 compatible).

       $SYSTEMD_PAGERSECURE
           Takes a boolean argument. When true, the "secure" mode of the pager is enabled; if
           false, disabled. If $SYSTEMD_PAGERSECURE is not set at all, secure mode is enabled if
           the effective UID is not the same as the owner of the login session, see geteuid(2)
           and sd_pid_get_owner_uid(3). In secure mode, LESSSECURE=1 will be set when invoking
           the pager, and the pager shall disable commands that open or create new files or start
           new subprocesses. When $SYSTEMD_PAGERSECURE is not set at all, pagers which are not
           known to implement secure mode will not be used. (Currently only less(1) implements
           secure mode.)

           Note: when commands are invoked with elevated privileges, for example under sudo(8) or
           pkexec(1), care must be taken to ensure that unintended interactive features are not
           enabled. "Secure" mode for the pager may be enabled automatically as describe above.
           Setting SYSTEMD_PAGERSECURE=0 or not removing it from the inherited environment allows
           the user to invoke arbitrary commands. Note that if the $SYSTEMD_PAGER or $PAGER
           variables are to be honoured, $SYSTEMD_PAGERSECURE must be set too. It might be
           reasonable to completely disable the pager using --no-pager instead.

       $SYSTEMD_COLORS
           Takes a boolean argument. When true, systemd and related utilities will use colors in
           their output, otherwise the output will be monochrome. Additionally, the variable can
           take one of the following special values: "16", "256" to restrict the use of colors to
           the base 16 or 256 ANSI colors, respectively. This can be specified to override the
           automatic decision based on $TERM and what the console is connected to.

       $SYSTEMD_URLIFY
           The value must be a boolean. Controls whether clickable links should be generated in
           the output for terminal emulators supporting this. This can be specified to override
           the decision that systemd makes based on $TERM and other conditions.

SEE ALSO

       systemd(1), systemd-userdbd.service(8), systemd-homed.service(8), nss-systemd(8),
       getent(1)

NOTES

        1. JSON User Records
           https://systemd.io/USER_RECORD

        2. JSON Group Records
           https://systemd.io/GROUP_RECORD

        3. User/Group Record Lookup API via Varlink
           https://systemd.io/USER_GROUP_API